Multiple image encryption based on multiplexing holography with Kramers–Kronig relations

Multiplexing techniques can store multiple wavefront information of object beams in one hologram, which is a way to realize multi-image encryption. In this paper, an optical multi-image encryption method based on Kramers-Kronig multiplexing digital holography is proposed. In the encryption process, multiple images are subjected to Fresnel diffraction at a certain distance and modulated by a random phase mask. The modulated images then interfere with the reference beam and form a noise-like compound ciphertext. In the decryption process, the information of the original images can be extracted directly from the positive frequency part of the spectrum. Compared to the traditional image encryption based on off-axis digital holography, this method enables the decryption of images in the case of spectrum overlap. The feasibility of our proposed method is demonstrated through numerical simulations, which provide a novel approach for the field of multi-image encryption based on digital holography.